Regensburg 2013 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
MM: Fachverband Metall- und Materialphysik
MM 31: Computational Materials Modelling - Diffusion & Kinetics II
MM 31.4: Vortrag
Mittwoch, 13. März 2013, 11:00–11:15, H24
Defect-domain wall interactions in ferroelectric materials — •Anand Chandrasekaran1,2, Dragan Damjanovic2, Nava Setter2, and Nicola Marzari1 — 1Theory and Simulation of Materials, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland — 2Ceramics Laboratory, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
Hardening and softening of ferroelectric materials can be engineered through the addition of dopants, and is a key technique to tailor dielectric and piezoelectric properties. Hardening is typically driven by the addition of acceptor dopants, and leads to small electromechanical coefficients and pinched hysteresis loops. Softening can be induced by the addition of donor dopants, which leads to large electromechanical coefficients and open hysteresis loops. Doping results in the formation of defects which interact with the domain walls present in the material. We use here first-principles calculations to show how acceptor dopants lead to the formation of defect complexes which align with the polarization axis and stabilize the ferroelectric domains. We corroborate the AC and DC conductivity data obtained in acceptor-doped materials with first-principles activation energies for the hopping of oxygen vacancies, obtained through nudged elastic-band calculations (NEB). We also calculate the NEB barrier energies for the movement of domain walls in the presence of various defects. As a result, we show how defects and defect associates can influence the mobility of domain walls leading to hardening or softening.